Radio aerial



Feb. 28, 195.0 E. DE FAYMOREAU ET AL A2,498,655

RADIO AERIAL `Filed July 11, 1947 A TTORN Y Patented Feb. 28,l 1950 UNITED STATES PATENT OFFICE RADIO AERIAL Application July 11, 1947, Serial No. 760,222 In France December 30, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires December 30, 1963 Claims.

The present invention relates to antenna devices and particularly to devices that comprise superposed orientable directed Wave antennas.

Antennas of this kind may, for example, be employed in direction finding devices, or in these combined with transmitting devices. It may be necessary to be able to rotate two or more aerial devices simultaneously.

According to one feature of the invention, the aerials are disposed on the same shaft and do or do not rotate simultaneouly.

According to other features of the invention, the superposed aerials are of the symmetrical type, and the symmetrical-asymmetrical devices consist of coaxial devices and are disposed along the axis of rotation of the assembled unit.

According to other features of the invention, the respective two symmetrical-asymmetrical connection devices of two superposed aerials are coaxial systems having such diameter ratios that the core of the outer device constitutes the external conductor of the inner device.

Numerous radio systems employ closely adjoining transmitting and receiving antennas. In certain cases, particularly in that of radio beacons, it is necessary for the transmitting and receiving antennas to rotate in synchronism around a shaft.

The invention applies particularly but not exclusively to this case. It provides means for disposing on the same shaft two groups of antennas, which can be made to rotate at the same speed or at different speeds.

For this purpose, the invention provides an assembly of devices for passing from a symmetrical circuit to an asymmetrical circuit, the same being illustrated in the one and only figure of the appended drawings.

In this figure, antennas I and 2 are respectively coupled to a receiver 3 and a transmitter `II. As can be seen in the drawing, transmitting antenna 2 is coupled to a device for passage from an electrically symmetrical system, such as that antenna, to an asymmetrical system, such as a coaxial transmission line. The external conductor 5 of the coaxial line is connected to the bottom part of antenna 2, while the top conductor of antenna 2 is connected to an impedance transformer element having a length equal to 1/4 of the operating wavelength. As can be seen in the drawing, the outer part of this coaxial conductor is joined by connections such as 'I to the outer part of the internal conductor 8 of the coaxial line formed by conductors 5 and 8.

A branching of these conductors is provided at 9 and I 0 to a coaxial cable that leads to transmitter Il. The internal conductor 3 constitutes the core I2 of another coaxial conductor consisting of the elements II and I2. These elements are connected to receiving antenna I in a manner similar to that shown at the bottom of the draw- The passage from the symmetrical transmission line terminating at antenna I to the asymmetrical transmission line consisting of conductors I I and I2 is effected by connections I3, which terminate at an internal core I4 that plays the same part in the impedance transformer associated to the receiver as the core in the impedance transformer associated to the transmitter.

The relative dimensions of the device are selected so that conductor I2 has the same dimensional ratio to conductor 6 as core ll has to core 8 associated to the transmitter.

The assembly of the impedance transformers associated to transmitting antenna 2 and receiving antenna I are mounted in the case taken as example on a movable support that makes it possible to rotate the assembly around the axis of the drawing.

For this purpose, the device is mounted on a ball bearing system shown schematically at l5.

The electric feeds are effected by means of a concentric contact shown at IG, I 1, I8, I1 and I8. It is to be noted that this device is not limited to the use of two groups of antennas, but that it is capable of being applied to any grouping of antennas. It is also to be noted that different impedance transformer devices may be employed without departing from the idea of the present invention.

Although the present invention has been described for one exampley of embodiment, it is evident that it is by no means limited thereto, but that the same is capable of variants and modilications Without departing from the scope of the invention.

We claim:

1.` An orientable arrangement comprising a plurality of N superposed antenna systems Where N is the number of systems each rigidly mounted on a mast structure, said mast structure comprising in spaced coaxial fixed relationship a vertical central conducting member and a plurality of coaxial tubular conducting members, there being one more of said conducting members than there are antenna systems, each said antenna system being coupled to a coaxial feeder comprised of two adjacent ones of said conductor members, the outer conductor of said feeder for the antenna system which is a certain number of systems counting from the top being the tubular conducting member which is the same number of conductor members counting from the centre, each said antenna system being shielded from its associated said coaxial feeder by only the said tubular member which is directly about said coaxial feeder, each said tubular member serving as coaxial feeder outer conductor being insulatingly sectionalised at the point of coupling to the associated antenna system, said arrangement further comprising a seating whereon said mast structure may be rotated about its own vertical axis to orientate said antenna systems, and sliprings means in said seating whereby said coaxial feeders are coupled to respective utilisation or energisation devices.

2, An antenna arrangement according to claim 1, wherein at least one of said antenna systems is electrically balanced, and wherein the tubular conducting member shielding said balanced antenna from its said associated coaxial feeder is connected, through a path of low impedance at the operating Wavelength, to the tubular member forming the outer conductor of said associated the foot of said mast to a point between said antennae systems such that the lower-antenna system but not the upper antenna system is shielded from the mast, coaxial feeder means mounted eoaxially with said mast for feeding separately said upper and said lower antennae systems, slipring .means connecting the conductors of said coaxial feeder means to respective antenna `uti- 4 lisation or energisation devices, and means to rotate said tubular shield member for orientation of said antenna systems.

4. An antenna arrangement according to claim 3, in which said coaxial feeder means comprises in spaced coaxial relation an inner conductor, an intermediate tubular conductor, and the conduct- -ing wall of said mast, said inner conductor and said intermediate conductor forming a coaxial Vfeeder serving to feed said upper antenna system, said intermediate conductor and said wall lof mast forming a coaxial feeder serving said 4, in which each said antenna system is electrically balanced, said tubular shield member being connected to the wall of the mast at two points substantially one quarter of the operating wavelength respectively above and below the feedpoint of said lower antenna system, said wall of mast being connected to the said intermediate conductor at two points substantially one quarter of the operating wavelength respectively above and below the feed-point of said upper antenna systems, said connections being of low impedance at the operating wavelength.

ETIENNE DE FAYMOREAU.

ANDRE' DE GOUVENAIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATESi PATENTS Number Name Dlate 2,311,472 Roosenstein Feb. 16, 1943 2,323,641 Bailey July 6, 1943 2,385,783 Alford Oct. 2, 1945 

